Data integration and processing for the first release was funded by the NC Floodplain Mapping Program.

Online_Linkage:

Description:

Abstract:

The NC Center for Geographic Information and Analysis developed this set of point ocations of bridges maintained by the NC Department of Transportation. Data from multiple sources were integrated to produce the best approximation of North Carolina's bridge inventory. This theme does not include culverts and other structures maintained by NC DOT.

Purpose:

This dataset was developed for the purpose of identifying bridges that may be affected by flood conditions. Bridges are part of the state's critical infrastructure and need to be included in natural hazard vulnerability analysis and risk assessments.

Supplemental_Information:

The North Carolina Floodplain Mapping Program supported the integration and processing of bridge data for inclusion in the Flood Inundation and Forecast Mapping System. Source data originated between 2001 and 2002 and was processed in stages during 2003 and 2004. Filename: bridges_nc.shp. This is the first published geospatial version of a statewide bridge inventory.

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date:
20040625

Currentness_Reference:

publication date

Status:

Progress:
Complete

Maintenance_and_Update_Frequency:
As needed

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate:
-84.401944

East_Bounding_Coordinate:
-75.587550

North_Bounding_Coordinate:
36.614184

South_Bounding_Coordinate:
33.767646

Keywords:

Theme:

Theme_Keyword_Thesaurus:
None.

Theme_Keyword:
bridge

Theme_Keyword:
infrastructure

Theme_Keyword:
transportation

Place:

Place_Keyword_Thesaurus:
None.

Place_Keyword:
North Carolina

Access_Constraints:
None.

Use_Constraints:

Acknowledgement of products derived form this data set should cite the following: The source of the bridge data is the North Carolina Center for Geographic Information and Analysis. Earlier versions of this data set may exist. The ser must be sure to use the appropriate data set for the time period of interest. While efforts have been made to ensure that these data are accurate and reliable within the state of the art, CGIA cannot assume liability for any damages or misrepresentation caused by any inaccuracies in the data or as a result of changes to the data caused by system transfers.

The bridge identification numbers from NCDOT and related attributes are presumed to be correct as of 2001 or 2002. Tabular data from the Bridge Maintenance Division were related to bridge identification numbers.

Logical_Consistency_Report:

The source data set from NC DOT GIS Unit was not documented. CGIA used ArcView software to check point locations in the context of detailed hydrography and NC DOT roads.

Completeness_Report:

The source data from NC DOT was not documented in terms of completeness. This dataset does not include bridges not maintained by NC DOT. CGIA did not use National Bridge Inventory data that was available in tabular format, presuming that the DOT bridges were included as a matter of course. If and when the National Bridge Inventory is geo-referenced, it merits a comparison to this data set to check for completeness.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

The point locations appear to be in the vicinity of related hydrography and road features. The base themes were mapped at 1:24,000 scale. The bridge source data were mapped at a scale no greater than 1:24,000 scale and perhaps at a smaller scale. Some point locations were greater than 100 feet from an apparent actual location based on the base maps.

Quantitative_Horizontal_Positional_Accuracy_Assessment:

Horizontal_Positional_Accuracy_Value:
24000

Horizontal_Positional_Accuracy_Explanation:

The scale of the base data against which the bridge locations were checked for accuracy was 1:24,000.

Data: Bridge1.shp: (Same as Bridge2.shp) A point coverage obtained from DOT-GIS in 2003. 18,136 records. 24 fields. Includes 5-digit ID (SIPS_id) and FIPS county number (DOT county numbers, also included, are different than FIPS county numbers).
Bridge_newid.shp: A point coverage obtained from Silvia Terziotti in August 2003; 14,483 records. 23 fields. Includes 5-digit ID (SIPS_id_1) from DOT-GIS files and 6-digit ID (newid) from DOT-Bridge Maintenance Division. The difference-newid has 4 digits (instead of 3) for bridge number (unique within a county) and two digits for county number. The newid will relate to Bridge Maintenance tabular data. The drawback is this file has fewer records than Bridge1.shp. Need to create a new 6-digit id for the records in Bridge1.shp.
Note: Although Bridge1.shp has many more records (culverts classified as bridges?) Bridge_newid.shp contains some points not included in bridge1.shp. Some appear to be miscoded (e.g., Craven county points far from Craven County). Some are points that coincide with Bridge1.shp points that have no meaningful attributes. Needs checking.
Bridgewdata.shp: A point theme with the same point locations as bridge_newid.shp. 14,483 records. 29 fields.
Bridgepolys_bridge1.shp: A polygon theme from DOT-GIS. 29,081 records (includes multiple polygons at some bridge location, e.g., two separate directions over a stream depicted by two polygons in this theme and a single point in the bridge point files). 6 fields including SIPS_id.
Spreadsheets from DOT include descriptions of some of the fields.
Processing
1. Create a 6-digit ID in bridge1.shp (18,136 records) to assign unique ids related to Bridge Maintenance tabular data. Open bridge1.dbf in EXCEL. Add and delete fields and concatenate as needed to create a join table with a 6-digit ID and selected fields to join to bridge1.dbf on the SIPS_id field.
2. Note: concatenate function requires the column in which the formula is placed to be formatted as "general" under the NUMBER tab. Save as spreadsheet (bridge1_dot_join6b.xls). Note: records 14161 through 14164 had no data. 14166 had duplicative data. Delete 5 rows. 18,131 records remain in spreadsheet.
3. Import spreadsheet into bridgeinventory2.mdb ACCESS database. Query for duplicate 6-digit ids (id_DOT6). None found. 18,131 records in tblBridgesDOT1withJoinFields.
4. Export DOT6_J1.dbf.
5. Also, delete duplicative rows in bridg1_dot_join6b.xls and save as dot_join6b.dbf.
6. Add the two dbf tables to ArcView. The one saved as dbf from EXCEL retained the desired formatting of number columns when added to ArcView. Use this one for joining.
7. Set theme properties for Bridge1.shp so that county name <> "". 18,131 records remain.
8. Join table dot_join6b.dbf to bridge1.shp.
9. Save as new shapefile: bridge_dot6_pts1.shp with 18,131 records.
10. To check the point locations before joining more data, use geoprocessing to do a spatial join, joining county name and number from cb100.shp. Convert to a shapefile: bridge_dot6_pts1co.shp.
11. A query in ArcView found that the COUNTY name in the DOT data did not match the joined county name by location for 205 of 18,131 records in bridge_dot6_pts1co.shp. Most of the 205 are right along a county boundary. There are some notable exceptions: Craven county records in Franklin County for example. Identify the points that are not along a county boundary.
12. To do more quality checking, do a spatial join, joining county name and number from cb100.shp to bridgewdata.shp (14,483 records). Convert to a shapefile: bridgewdata_co.shp. Identify the points in bridgewdata_co.shp that do not coincide with a point in bridge_dot6_pts1co.shp.
13. Delete redundant fields in bridge_dot6_pts1co.shp resulting from the joins, and drop fields not needed for this project. (Retain copy of dbf with all joined fields as bridge_dot6_pts1co_allfields.dbf).
Fields dropped from bridge_dot6_pts1co.shp: FIPS (with decimals); DIVISION (with decimals);OWNER (with decimals); COUNTY_NUM (with decimals); BRIDGE_NUM (with decimals); OVER_UNDER (with decimals); YEAR_BUILT (with decimals); PROJECT_NU; WIDTH (with decimals); BRIDGE_NUM; POSTED_SV; POSTED_TTS; MIN_CLR_VE; FEATURE_IN (second); FACILITY_C (second); LOCATION (second); CO_; SORT; CB100; CB100_ID; AREA; PERIMETER; CO_NAME; CO_ABBR; ACRES;
14. Identify six points in Franklin County that should have been in Craven County. Research correct locations and move points accordingly. (Corrected shapefile: /volume2/ncem/floodwarning/cheryl/dotfixed.shp*).
15. Identify and fix points in bridgewdata_co.shp. Copied bridgewdata.shp and converted to coverage. Checked against bridge_dot6 data to see if any points in bridgewdata were not in bridge_dot6. SIPS_ID 83051 is the only label in bridgewdata not in bridge_dot6.
Duplicate points were found in the bridgewdata coverage:
The points on each side of another bridge were resolved by moving one of the points toward the center of the two bridges and deleting the duplicate point.
The points that had duplicate SIPS_Ids were resolved. The point that did not have a corresponding point in the bridge_dot6 data had a "d" added at the end of the SIPS_ID to indicate a duplicate.
Also, wdfixed.shp (and coverage) - bridgewdata with duplicates resolved.
A new shapefile was created for 10,938 records for which type = "O" or DOT normal bridges. Culverts and other structures are not included in this final set.

NCCGIA is charged with the development and maintenance of the State's corporate geographic database and, in cooperation with other mapping organizations, is committed to offering its users accurate, useful, and current information about the state. Although every effort has been made to ensure the accuracy of information, errors and conditions originating from physical sources used to develop the corporate database may be reflected in the data supplied. The client must be aware of data conditions and bear responsibility for the appropriate use of the information with respect to possible errors,original map scale, collection methodology, currency of data, and other conditions specific to certain data.
NCCGIA does not support secondary distribution of these data. The use of trade names or commercial products does not constitute their endorsement by the NCCGIA or North Carolina State Government.

Data creation and large data analysis jobs contact Database Administration P:(919)733-2090. All data are available through standard ordering procedures on a cost recovery basis.

Technical_Prerequisites:

All formats supplied are created using ARC/INFO GIS software on Unix workstations or ArcGIS on Windows PCs. Other formats are available. Format compatibility is the user's responsibility. For more information on formats and media, use a web browser:
http://www.cgia.state.nc.us/cost.html